Deserts may look barren and lifeless, but a surprising number of plants grow in the arid regions of the world. According to the University of California, deserts fall into one of four types: hot, semi-arid, coastal or cold. All deserts receive 20 inches or less of rainfall annually. The harsh conditions make it imperative that the plants adapt to extreme conditions in order to survive.
Most wildflowers bloom in the spring after the rain falls. The flowers attract bees and other pollinators who help the plants reproduce by carrying pollen from one plant to another. According to DesertUSA, Butterflies rely on the plants, too, including the Mojave aster. Black caterpillars with gray and orange stripes feed on the nectar of the plant before they turn into the Desert Checkerspot, a small orange butterfly. Another flower, the fragrant white-blossomed desert evening primrose relies on the White-lined Sphynx moth to pollinate it.
Cactus thrive in the desert where their drought-resistant tendencies really shine. Some cactus grow barrel-shaped, such as the barrel cactus, one of the largest cactus in North American deserts. While the plant features lots of spines, the yellow flowers that appear on the top of the plant do not contain spines, allowing insects to pollinate the plant. Prickly pear cactus also grows in the desert where it provides an important food source for both wildlife and humans. Another cactus, the saguaro, grows slowly but steadily up to 50 feet in height. The saguaro stores enough water to allow it to bloom every year, unlike some desert plants that will not bloom if they do not have enough water. Each flower on the saguaro opens in the evening, then closes again by midday the following day, never to open again, according to the Lady Bird Johnson Wildflower Center. To achieve pollination, the flowers attract bats and insects that pollinate it during the night or early morning.
The shrubs or bushes of the desert tend to grow much smaller than those found in other areas of the world. Many of the shrubs feature a bad taste, stopping wildlife and birds from eating all of their leaves and twigs. Many of the shrubs, including sagebrush, creosote bush and mesquite, rely on silvery or glossy leaves and spiny branches that allow them to deflect some of the sun's energy, according to the Utah State Historical Society. Some shrubs, such as the turpentine bush and brittle bush, only open their leaves at night when evaporation rates are lower.
Few trees grow in the desert, but those that do often look very different in the desert. Desert trees, such as the Rio Grande cottonwood, usually grow close to water or areas that flood during the brief rainy season. According to DesertUSA, the tree produces as many as 25 millions seeds, relying on the seed's little white tufts resembling parachutes to help the seeds disperse in the wind. Since the seeds must fall on moist ground in order to grow, very few seeds survive. While the seeds may not survive, they provide an important food source for deer, rabbits and mice while larger trees provide suitable nesting habitat for birds.